Tabel . Some important Minerals in Soils
Name
Formula
Primary Minerals
Quartz
SiO2
Feldspar :
- Orthoclase
- Plagioclase
(K, Na)AlSi3O8
(Ca, Na)Al(Al, Si)Si2O8
Micas :
- Muscovite
- Biotite
Dark Mineral (Augite,
hornblende, Biotite,
Mica, Others)
Apatite
Calcite, Dolomite,
Gypsum
KAl3Si3O10(OH)2
KAl(Mg, Fe)4Si3O10(OH)2
Ca2(Al,Fe)4(Mg,Fe)4Si6O24
3Ca3(PO4)2.CaF2
See secondary minerals
Calcite
Dolomite
Secondary Minerals
CaCO3
(Ca,Mg)(CO3)2
Gypsum
CaSO4.2H2O
Iron Oxides
Fe2O3.xH2O
Quartz
SiO2
Clay :
Kaolinite, Illite,
Montmorillonite,
Vermicullite,
(Complex)
1
Comments
Hard, weathers slowly,
major material of most
sands
Hard, weather slowly or
moderately, but provide
important nutrients and
clay in the weathered
products.
“Glitter” in rocks or wet
sands. Important source
of potassium and clay
Includes several minerals
that weather moderately
fast; good clay formers
The
most
common
mineral
supplying
phosphorus
Can be either primary or
secondary
Slightly soluble materials
in limestone or dolomite
rock common in aridregion soils; calcium or
magnesium source
A soft, moderately soluble
mineral found in aridregion soils
A group of minerals with
different
amounts
of
water giving soils their
yellow-to-red colors; iron
source
Reprecipitated forms such
as
opal,
agate,
and
petrified wood
Tabel 1. Stage pelapukan mineral pada fraksi tanah < 2 mm
Stage
Stage Awal
1
2
3
4
5
Stage intermediate
6
7
8
9
Tipe mineral
Karakter Tanah
Gipsum
Kalsit
Hornblende
Biotit
Albit
Mineral ini terdapat di
fraksi debu dan clay
pada tanah muda dan
tanah di daerah arid
dimana air kurang shg
menghambat pelapukan
kimia dan pencucian
(leaching)
Kuarsa
Muskovit (termasuk ilit)
Vermikulit
Montmorillonit
Stage lanjut (advanced stage)
10
Kaolinit
11
Gibsit
12
Hematit (juga gutit)
13
Anatase
2
Tanah banyak
ditemukan didaerah
temperate; umumnya
subur, rumput atau
hutan sbg vegetasi
alaminya
Fraksi clay pada tanah
yang terlapukkan lanjut
di
daerah
tropik,
kesuburan rendah
Table. Letter Horizons Most Commonly Encountered in Soils
New
Old
Description
Usually Surface Horizons
Oi, Oe
O1
Organic horizon in which most leaves, stems, fruits, and
other plant parts are still identifiable (includes recent
litter). Usually quite thin-a centimeter or so thick
Oa, Oe
O2
Organic horizon so extensively altered that identification of
the parts of plant materials is not usually possible. Can be
many centimeters thick.
A
A1
Mineral horizon darkened by organic matter accumulation.
Under Oa horizons, it is usually thin; in cultivated soil it is
the surface horizon and may be labeled Ap. An Ap horizon
may be a mixture of several thin horizons, even including
part of a shallow B.
Usually Subsurface Horizons
E
A2
A Mineral horizon lighter colored than an A or Oa above it
or B below it. Fine clay and minute organic substances
have been washed (eluviated, leached) out of it by
percolating waters. Usually common in high-rainfall areas,
especially under forests
AB or EB
A3
A transition horizon more like the A or E above it than
like the B below it
BA or BE
B1
A transition horizon more like the B below it than like the
A or E above it
B or Bw
B2
Layer of illuvial colloids (accumulation) or evidence of
weathering below the A horizon (s). Small particles that
have washed from the O, A, or E horizons have
accumulated because of filtration (lodging) or lack of
enough water to move them deeper. Early B horizon
development stages of soils may have only redder
3
(orange, yellow, brown) colors of weathering caused by
the colored iron hydrous oxides. Often higher in clay than
the A. always higher in clay than the E; the top of the B
may start at a depth ranging from about 15-50 cm below
the soil surface
BC or CB
B3
C
C
A transition horizon from B to C horizons
Unconsolidated material (unless consolidated during soil
development by carbonates, silica, gypsum, or other
material) below A or B horizons. Little evidence of profile
development.
R
R
Underlying consolidated (hard) rock. Cr for softer material.
Horizon subscripts
Subscripts are added to letter horizons for further detail, always as lowercase
letters. For example :
New
k
Old
ca
Descripton
A depositional accumulation of calcium and magnesium
carbonates (lime)
g
g
Strong gleying, which is a result of long-time poor
aeration, usually because of excess water. Soil colors are
grays to pastel blues and greens. Ex : Cg
h
h
Deposited (illuvial) humus from percolating water (Bh)
t
t
Deposit (illuvial) clay from horizons above, usually labeled
as Bt
x
x
Fragipan (hard, silty texture, brittle hardpan)
m
m
Strong cementation into hardpan (as by carbonates,silica)
4
Table. Brief characterizations of the 11 Soil Orders
Soil Order
Entisol
General Features
Entisols have no profile development except perhaps a
shallow marginal A. Many recent river floodplains,
volcanic ash deposits, unconsolidated deposits with
horizons eroded away, and sands are Entisols
Inceptisols
These soils, especially in humid regions, have weak to
moderate horizon development. Horizon development
has
been
waterlogged
retarded
soils,
development.
Andisols
A tentative soil order.
5
or
because
lack
of
of
cold
time
for
climates,
stronger